1. Field of the Invention
The invention relates to a headset for hearing protectors according to the preamble of claim 1.
2. Description of Background Art
Maintaining on-line radio telephone communication in situations necessitating the use of different kinds of protectors, such as hearing protectors and respirators as well as helmets and protective clothing, is difficult, or, in fact, almost impossible without auxiliary equipment. The term `auxiliary equipment` refers to an earphone/microphone combination coupled with a built-in speaker and microphone in the radiotelephone or used to replace these altogether. Such combined microphones and earphones have been used almost since radio telephones became available. They have been manufactured by both radio telephone manufacturers and specialized companies. The best-known user groups include air pilots as well as drivers of military vehicles and signallers. Used by civilians, such combinations have become more common along with the increased use of radio telephones and wireless and line telephones.
The above-mentioned increased use of protectors and protective clothing as well as the need for a hands-free mode for reasons of occupational safety impose new requirements on the compatibility of the combinations in different work situations. Thus far, commercially manufactured built-in earphone/microphone combinations have been available in hearing protectors. The manufacturers of such combinations have themselves almost invariably been manufacturers of hearing protectors.
The following features are characteristic of such prior art hearing protectors equipped with a microphone and an earphone:
a) The cups of the hearing protectors are pressed over the user's ears by means of the springback force generated by the bow connecting them; PA1 b) The inside of the cups is provided with a sound-absorbing material, usually expanded plastic, and depending on the size of the cup and the amount of said material, different degrees of damping are attained depending on the audio frequency in question; PA1 c) The edge of the cup is rimmed with a annular, typically elliptic padding which during use closes the inside of the cup against the user's cheek. PA1 a) a laryngophone (throat microphone) fixed to a collar worn round the user's neck. The disadvantage here is that the earphone is placed in the auditory canal where it as a result of prolonged use causes irritation and requires hygienic measures to be taken. In order to function in a satisfactory manner, the laryngophone requires a certain pressure and careful adjustment into position which in turn often results in discomfort during use. PA1 b) A separate microphone attached to the user's collar as close to his/her mouth as possible, whereby such a microphone needs to be of the noise compensated kind so as to perform in noisy conditions, and whereby the microphone needs to be placed such that background sounds reach the microphone from all directions. The drawback involved herein, in addition to the above-cited problems related to the earphone itself, lies with the risks of the separate wires being exposed to unwanted traction. PA1 c) The earphone itself which from inside the ear captures acoustic vibration transmitted from the vocal chords to the ear cavity through cavities in the head. When transmitting, the weak signal generated in the ear capsule requires amplification and its frequency pattern needs to be modified to comply with the transmitter modulator. In addition to the above-cited problems relating to the earphone, the solution is hampered by the amplifier structure, protection, and current supply. Regardless of the drawbacks, this solution is a practical and simple one in short-term use. PA1 d) A separate microphone placed in the same piece with the earphone and responding to the vibration of the ear bone. The weak signal requires amplification and its frequency pattern must be modified to comply with the modulator of the radio telephone transmitter. The drawbacks and advantages are as cited under c).
The aforementioned fixedly mounted earphone/microphone combinations (headsets) in the protective cups necessitate changes, namely piercing, machining, and glueing, etc., to be performed on the cups and the bow. Such units are manufactured in various European countries, the USA, Japan and South Korea.
Headsets of the above-described kind are mainly hampered by their complexity and expensiveness, where a restricted supply limits competition. As manufacturers only provide integral units, each alternating user requires personal equipment even where only momentary use occurs.
Other prior-art solutions applied in combination with hearing protectors are based on an earphone in the user's ear equipped with a wire between the padding and the user's cheek. In such solutions, the microphone is constituted by the following
Integral headsets generally referred to as "light headsets" are as such not fitted for use with hearing protectors due to either their mechanical structure or the fact that they impair the noise abatement properties of the hearing protectors.